Pär Hallberg

A signal for an abuse liability for pregabalin—results from the Swedish spontaneous adverse drug reaction reporting system

PurposePregabalin is a gamma-aminobutyric acid (GABA) analogue approved for the treatment of epilepsy, neuropathic pain and generalised anxiety disorder. As a GABA analogue, there has been some concern about an abuse liability. We aimed to investigate the possible abuse liability of pregabalin.MethodsBy applying a Bayesian data-mining algorithm to reports of possible drug abuse or addiction in the Swedish national register of adverse drug reactions (SWEDIS), we calculated the information component (IC) for pregabalin and reports of abuse and addiction.ResultsOut of 198 reports indicative of abuse or addiction to any drug, 16 concerned pregabalin. The IC became significantly elevated in the fourth quarter of 2008, rising to 3.99 (95% confidence interval 3.21–4.59) at the end of 2009.ConclusionBased on the signal from the present study, we conclude that pregabalin is likely to be associated with an abuse potential.

Digoxin and mortality in atrial fibrillation: a prospective cohort study

ObjectiveThe Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study showed that rhythm-control treatment of patients with atrial fibrillation (AF) offered no survival advantage over a rate-control strategy. In a subgroup analysis of that study, it was found that digoxin increased the death rate [relative risk (RR) = 1.42), but it was suggested that this may have been attributable to prescription of digoxin for patients at greater risk of death, such as those with congestive heart failure (CHF). No study has investigated a priori the effect of digoxin on mortality in patients with AF. This study aimed to address this question.MethodsUsing data from the Registry of Information and Knowledge about Swedish Heart Intensive care Admissions (RIKS-HIA), we studied the 1-year mortality among patients admitted to coronary care units with AF, CHF, or AF+CHF with or without digoxin (n = 60,764) during 1995–2003. Adjustment for differences in background characteristics and other medications and treatments was made by propensity scoring.ResultsTwenty percent of patients with AF without CHF in this cohort were discharged with digoxin. This group had a higher mortality rate than the corresponding group not given digoxin [adjusted RR 1.42 (95% CI 1.29–1.56)], whereas no such difference was seen among patients with CHF with or without AF, although these patients had a nearly three-times higher mortality.ConclusionThe results suggest that long-term therapy with digoxin is an independent risk factor for death in patients with AF without CHF.

The CYP2C9 genotype predicts the blood pressure response to irbesartan: results from the Swedish Irbesartan Left Ventricular Hypertrophy Investigation vs Atenolol (SILVHIA) trial

Background The cytochrome P450 CYP2C9 enzyme (CYP2C9) metabolizes many clinically important drugs, for example, phenytoin, warfarin and the angiotensin II type 1 (AT1) receptor antagonists, losartan and irbesartan. Single nucleotide polymorphisms in the CYP2C9 gene result in the expression of three important variants, CYP2C9*1 (wild-type), CYP2C9*2 and CYP2C9*3, the last two exhibiting reduced catalytic activity compared with the wild-type. The CYP2C9 genotype is known to determine sensitivity to and dose requirements for both warfarin and phenytoin, and also the rate of metabolism of losartan. However, its influence on clinical response to treatment with the AT1 receptor antagonist, irbesartan, has not been investigated. Objective To determine whether the CYP2C9 genotype influences the blood pressure-decreasing response to antihypertensive treatment with irbesartan. Design and methods One hundred and two patients with essential hypertension and left ventricular hypertrophy were allocated randomly to groups to receive double-blind treatment with either irbesartan (n = 49) or the β1-adrenergic receptor blocker, atenolol (n = 53). Blood pressure was measured before and after 12 weeks of treatment. CYP2C9 genotyping was performed using solid-phase minisequencing. Results The diastolic blood pressure (DBP) response differed in relation to the CYP2C9 genotype in patients given irbesartan: the reduction in patients with genotype CYP2C9*1/ CYP2C9*1 (n = 33) was 7.5% and that with CYP2C9*1/ CYP2C9*2 (n = 12) was 14.4% (P = 0.036). A similar trend was seen for systolic blood pressure. In contrast, no relation was seen between the CYP2C9 genotype and blood pressure response to atenolol, a drug not metabolized via CYP2C9. Conclusions The CYP2C9 genotype seems to predict the DBP response to irbesartan, but not to atenolol, in patients with essential hypertension.

Association between the number of coadministered P-glycoprotein inhibitors and serum digoxin levels in patients on therapeutic drug monitoring

BackgroundThe ABC transporter P-glycoprotein (P-gp) is recognized as a site for drug-drug interactions and provides a mechanistic explanation for clinically relevant pharmacokinetic interactions with digoxin. The question of whether several P-gp inhibitors may have additive effects has not yet been addressed.MethodsWe evaluated the effects on serum concentrations of digoxin (S-digoxin) in 618 patients undergoing therapeutic drug monitoring. P-gp inhibitors were classified as Class I, with a known effect on digoxin kinetics, or Class II, showing inhibition in vitro but no documented effect on digoxin kinetics in humans. Mean S-digoxin values were compared between groups of patients with different numbers of coadministered P-gp inhibitors by a univariate and a multivariate model, including the potential covariates age, sex, digoxin dose and total number of prescribed drugs.ResultsA large proportion (47%) of the digoxin patients undergoing therapeutic drug monitoring had one or more P-gp inhibitor prescribed. In both univariate and multivariate analysis, S-digoxin increased in a stepwise fashion according to the number of coadministered P-gp inhibitors (all P values < 0.01 compared with no P-gp inhibitor). In multivariate analysis, S-digoxin levels were 1.26 ± 0.04, 1.51 ± 0.05, 1.59 ± 0.08 and 2.00 ± 0.25 nmol/L for zero, one, two and three P-gp inhibitors, respectively. The results were even more pronounced when we analyzed only Class I P-gp inhibitors (1.65 ± 0.07 for one and 1.83 ± 0.07 nmol/L for two).ConclusionsPolypharmacy may lead to multiple drug-drug interactions at the same site, in this case P-gp. The S-digoxin levels increased in a stepwise fashion with an increasing number of coadministered P-gp inhibitors in patients taking P-gp inhibitors and digoxin concomitantly. As coadministration of digoxin and P-gp inhibitors is common, it is important to increase awareness about P-gp interactions among prescribing clinicians.

Genetic variants associated with antithyroid drug-induced agranulocytosis: a genome-wide association study in a European population

BACKGROUND Drug-induced agranulocytosis is a potentially life-threatening adverse reaction. Genome-wide association studies (GWASs) in ethnic Chinese people in Taiwan and Hong Kong have shown an association between agranulocytosis induced by antithyroid drugs and the HLA alleles HLA-B*38:02 and HLA-DRB1*08:03. We aimed to identify genetic variants associated with antithyroid drug-induced agranulocytosis in a white European population. METHODS We did a GWAS in 234 European adults with any non-chemotherapy drug-induced agranulocytosis (absolute neutrophil count ≤0·5 × 10(9)/L [≤500/μL]) and 5170 population controls. 39 of the 234 patients had agranulocytosis that was induced by antithyroid drugs (thiamazole [methimazole], carbimazole, or propylthiouracil). After imputation and HLA allele prediction, 9 380 034 single nucleotide polymorphisms (SNPs) and 180 HLA alleles were tested for association. The genome-wide significance threshold was p<5 × 10(-8). FINDINGS Agranulocytosis induced by non-chemotherapy drugs in general was significantly associated with the HLA region on chromosome 6, with odds ratios (ORs) of 3·24 (95% CI 2·31-4·55, p=1·20 × 10(-11)) for HLA-B*27:05 and 3·57 (2·61-4·90, p=2·32 × 10(-15)) for the top SNP (rs114291795). Drug-specific analysis showed that the association with HLA-B*27:05 was largely driven by cases induced by antithyroid drugs. In a multiple logistic regression model, the OR for HLA-B*27:05 was 7·30 (3·81-13·96) when antithyroid drug-induced agranulocytosis was compared with population controls (p=1·91 × 10(-9)) and 16·91 (3·44-83·17) when compared with a small group of hyperthyroid controls (p=5·04 × 10(-4)). Three SNPs were strongly associated with antithyroid drug-induced agranulocytosis: rs652888 (OR 4·73, 95% CI 3·00-7·44, p=1·92 × 10(-11)) and rs199564443 (17·42, 7·38-41·12, p=7·04 × 10(-11)), which were independent of HLA-B*27:05, and rs1071816 (5·27, 3·06-9·10, p=2·35 × 10(-9)) which was in moderate linkage disequilibrium with HLA-B*27:05. In heterozygous carriers of all three SNPs, the predicted probability of antithyroid drug-induced agranulocytosis was about 30% (OR 753, 95% CI 105-6812). To avoid one case of agranulocytosis, based on the possible risk reduction if all three SNPs are genotyped and carriers are treated or monitored differently from non-carriers, roughly 238 patients would need to be genotyped. INTERPRETATION In white European people, antithyroid drug-induced agranulocytosis was associated with HLA-B*27:05 and with other SNPs on chromosome 6. In the future, carriers of these variants could be placed under intensified monitoring or offered alternative treatment for hyperthyroidism. FUNDING Swedish Research Council, Swedish Heart and Lung Foundation, Clinical Research Support at Uppsala University, German Federal Institute for Drugs and Medical Devices, Carlos III Spanish Health Institute, European Regional Development Fund, UK National Institute for Health Research, The Selanders Foundation, Thuréus Foundation, European Commission, and Science for Life Laboratory.

Association of Spironolactone Use With All-Cause Mortality in Heart Failure A Propensity Scored Cohort Study

Background—In 3 randomized controlled trials in heart failure (HF), mineralocorticoid receptor antagonists reduced mortality. The net benefit from randomized controlled trials may not be generalizable, and eplerenone was, but spironolactone was not, studied in mild HF. We tested the hypothesis that spironolactone is associated with reduced mortality also in a broad unselected contemporary population with HF and reduced ejection fraction, in particular New York Heart Association (NYHA) I–II. Methods and Results—We prospectively studied 18 852 patients (age 71±12 years; 28% women) with NYHA I–IV and ejection fraction <40% who were registered in the Swedish Heart Failure Registry between 2000 and 2012 and who were (n=6551) or were not (n=12 301) treated with spironolactone. We derived propensity scores for spironolactone treatment based on 41 covariates. We assessed survival by Cox regression with adjustment for propensity scores and with matching based on propensity score. We performed sensitivity and residual confounding analyses and analyzed the NYHA I–II and III–IV subgroups separately. One-year survival was 83% versus 84% in treated versus untreated patients (log rank P<0.001). After adjustment for propensity scores, the hazard ratio for spironolactone was 1.05 (95% confidence interval, 1.00–1.11; P=0.054). Spironolactone interacted with NYHA (P<0.001). In the NYHA I–II subgroup, after adjustment for propensity scores, the hazard ratio for spironolactone was 1.11 (95% confidence interval, 1.02–1.21; P=0.019). Conclusions—In an unselected contemporary population of HF with reduced ejection fraction, spironolactone was not associated with reduced mortality. The net benefits of spironolactone may be lower outside the clinical trial setting and in milder HF.

Cystatin C vs creatinine as markers of renal function in patients on digoxin treatment

Background: The kidney function is a major determinant of the serum concentration of digoxin as this drug is mainly eliminated unchanged through the kidneys. Since digoxin is widely prescribed among the elderly, and the glomerular filtration rate (GFR) declines with age, it is important that the clinician takes the patients GFR into account when prescribing digoxin. Serum cystatin C has been suggested to be superior to creatinine for estimation of GFR, which may have relevance for the optimization of treatment with digoxin. Methods: To evaluate which of the two GFR markers serum creatinine and serum cystatin C that best correlates with serum digoxin, we compared the serum levels of digoxin with the serum levels of creatinine and cystatin C in 149 patients on therapeutic drug monitoring of digoxin at our hospital. Results: Overall, there was a stronger correlation between serum digoxin concentrations and cystatin C (p=0.00001) as compared to creatinine (p= 0.00003). Interestingly, of the patients with a serum digoxin concentration 1.5 nmol/L, 29% had a serum creatinine level within normal limits, as compared to 20% with normal cystatin C levels. Conclusions: In this study, serum cystatin C correlated better to serum digoxin than did serum creatinine. With improved GFR monitoring, digoxin concentrations should be better controlled.

Adipocyte-derived leucine aminopeptidase genotype and response to antihypertensive therapy

BackgroundAdipocyte-derived leucine aminopeptidase (ALAP) is a recently identified member of the M1 family of zinc-metallopeptidases and is thought to play a role in blood pressure control through inactivation of angiotensin II and/or generation of bradykinin. The enzyme seems to be particularly abundant in the heart. Recently, the Arg528-encoding allele of the ALAP gene was shown to be associated with essential hypertension.MethodsWe evaluated the influence of this polymorphism on the change in left ventricular mass index in 90 patients with essential hypertension and echocardiographically diagnosed left ventricular hypertrophy, randomised in a double-blind study to receive treatment with either the angiotensin II type I receptor antagonist irbesartan or the beta1-adrenoceptor blocker atenolol for 48 weeks. Genyotyping was performed using minisequencing.ResultsAfter adjustment for potential covariates (blood pressure and left ventricular mass index at baseline, blood pressure change, age, sex, dose and added antihypertensive treatment), there was a marked difference between the Arg/Arg and Lys/Arg genotypes in patients treated with irbesartan; those with the Arg/Arg genotype responded on average with an almost two-fold greater regression of left ventricular mass index than patients with the Lys/Arg genotype (-30.1 g/m2 [3.6] vs -16.7 [4.5], p = 0.03).ConclusionsThe ALAP genotype seems to determine the degree of regression of left ventricular hypertrophy during antihypertensive treatment with the angiotensin II type I receptor antagonist irbesartan in patients with essential hypertension and left ventricular hypertrophy. This is the first report of a role for ALAP/aminopeptidases in left ventricular mass regulation, and suggests a new potential target for antihypertensive drugs.

Phenotype Standardization of Angioedema in the Head and Neck Region Caused by Agents Acting on the Angiotensin System

Angioedema is a potentially life‐threatening adverse reaction to angiotensin‐converting enzyme inhibitors and angiotensin receptor blockers. To study the genetic etiology of this rare adverse event, international consortia and multicenter recruitment of patients are needed. To reduce patient heterogeneity, we have standardized the phenotype. In brief, it comprises swelling in the head and neck region that first occurs during treatment. It should not coincide with urticaria or have another likely cause such as hereditary angioedema.

Gender related difference in the risk of bisphosphonate associated atypical femoral fracture and osteonecrosis of the jaw

Gender related difference in the risk of bisphosphonate associated atypical femoral fracture and osteonecrosis of the jaw